Orthodontic brackets represent a principal component of all corrective orthodontic treatments devoted to improving a patient's occlusion. Conventional orthodontic treatments affix brackets to the patient's teeth and an archwire is threaded through a slot of each bracket. The archwire applies corrective forces that coerce the teeth to move to orthodontically correct positions. Traditional ligatures, such as small elastomeric O-rings or fine metal wires, are employed to retain the archwire within each bracket slot. Due to difficulties encountered in applying an individual ligature to each bracket, self-ligating orthodontic brackets have been developed that eliminate the need for ligatures by relying on a movable latch or slide for captivating the archwire with the bracket slot.
Conventional orthodontic brackets are ordinarily formed from stainless steel, which is strong, nonabsorbent, weldable, and relatively easy to form and machine. Patients undergoing orthodontic treatment using metal orthodontic brackets, however, may be embarrassed by the visibility of conventional metal orthodontic brackets, which are not cosmetically pleasing. To improve the cosmetic appearance, certain conventional orthodontic brackets incorporate a bracket body of a transparent or translucent non-metallic material, such as a polymer resin or a ceramic, that assumes or mimics the color or shade of the underlying tooth. Such orthodontic brackets may rely upon a metallic insert lining the archwire slot for strengthening and reinforcing the bracket body in the vicinity of the archwire slot. As a result, the appearance of metal in the patient's mouth is less noticeable in ordinary view and, therefore, brackets characterized by a non-metallic bracket body are more aesthetically pleasing. However, conventional orthodontic brackets with non-metallic bracket bodies have yet to implement self-ligation as self-ligating brackets necessitate the use of metallic materials because of the strength, ductility and toughness of metals as compared to other non-metallic materials.
Conventional self-ligating orthodontic brackets suffer from other deficiencies. For example, certain self-ligating brackets apply a spring force to hold a ligating slide in a closed position to captivate an archwire. When the ligating slide is moved from the closed position to an open position, the spring force continues to act against the ligating slide and opposes the movement.
Thus, there would be a need for a self-ligating orthodontic bracket that overcomes these deficiencies of conventional self-ligating orthodontic brackets.